The invention concerns a primary dressing for moist wound care in the form of a lattice or netting containing elongate bodies of silicone and optionally active ingredients and/or dyes embedded therein, as well methods for its manufacture.
Chronic wounds that generate a lot of exudate and in which a granulation is to be promoted are treated according to the principle of moist wound care. In this context, a wound dressing is placed onto the wound that is suitable for absorbing wound secretion, prevents drying out of the wound surface, and maintains the physiological wound environment in this way. The healing process of the wound is coupled with vessel growth, fibroblast growth, and epithelial growth which grow in the wound for forming new tissue. When the wound during the healing process is covered with a fine-fiber wound dressing, there is, on the one hand, the risk of infections by growth of tissue into the fibers of the wound dressing. On the other hand, upon growth of tissue into the wound dressing, a non-traumatic removal of the wound dressing is not possible and the wound surface, upon removal of the wound dressing, is destroyed and the healing process is thereby prolonged.
For promoting granulation, in wound treatment open pore foam materials are used that adhere to the base of the wound. Hydrophilic foam materials ensure by increased capillary action a fast transport of the exudate to the exterior and ensure in this way a balanced moist wound environment. Due to the open pore structure, there is however the risk of ingrowth with the wound.
Functional wound dressings are constructed of three elements: primary dressing, secondary dressing and fixation. The primary dressing when in use is lying directly on the wound and is supposed to maintain a moist wound environment and transport away excess exudate from the wound. The primary dressing may not adhere to the wound so that a non-traumatic removal of the wound dressing is possible. The secondary dressing which is arranged on the side of the primary dressing which is facing away from the wound contains the absorptive body, for example, an open pore foam material that absorbs the wound exudate. Optionally, the secondary dressing comprises also a distribution layer which in use is positioned between primary dressing and absorptive body and which ensures a uniform distribution of the wound exudate. In order to prevent leaking through the dressing to the exterior, in the secondary dressing, on the side that is facing away from the wound, a liquid-impermeable but breathable protective layer is optionally arranged. In order to secure the position of the primary and secondary dressings during wound treatment, a bandage is applied. Suitable materials for the fixation are fixation bandages, tubular bandages, or adhesive fixation bandage
The composition of the primary dressing which is lying directly on the wound is of enormous importance for the healing process. For preventing that the primary dressing will adhere to the surface of the wound, porous primary dressings with a hydrophobic silicone surface are proposed. Silicones are biocompatible and do not cause inflammation reactions. Due to their hydrophobic surface, cells cannot adhere, or only minimally adhere, to the surface of the silicone. They do not stick to the wound and enable in this way a non-traumatic removal. As a result of their excellent vapor permeability, silicones are particularly breathable. Through the pores, the wound exudate can be transported away well.
DE 4407031 A1 discloses a siliconized fiber nonwoven which is comprised of a support material of synthetic fibers, in particular polyester or polypropylene, and a silicone coating applied thereto at one or both sides. During manufacture, the support material is coated with a solvent-free addition-crosslinked silicon. In this way, on the fiber nonwoven a smooth surface is produced that advantageously should not stick to the wound surface.
WO 87/05206 discloses a primary dressing which comprises a stabilizing elastic netting with a hydrophobic gel layer, in particular a silicone gel layer or polyurethane gel layer. In this context, the netting is required on the one hand for stabilization and serves on the other hand for providing the pore system which is required for transporting the wound exudate through the primary dressing. Into the hydrophobic gel layer antibacterial active ingredients or substances that promote wound healing may be embedded. In order to avoid infections by fibers that become detached from the netting, it is required that the hydrophobic gel layer envelopes the netting completely (without any defects). Due to the hydrophobic gel layer, the fixation on the wound site is ensured, on the one hand; on the other hand, in particular because of the adhesion of the primary dressing due to the gel, there is the risk that the wound site will be damaged by removal of the primary dressing.
As a further development of WO 87/05206, EP 0633758 B1 discloses, as a protection against leaking, a wound bandage with a primary dressing of an elastic textile netting which, in analogy to WO 87/05206, is coated with and enveloped by a hydrophobic silicon gel layer. Furthermore, the wound dressing according to EP 0633758 B1 comprises an absorbent body (absorptive body) and a liquid barrier layer.
Wound dressings according to DE 4407031 A1, WO 87/05206, and EP 0633758 B1 have in common that they have a porous support structure that is provided with a silicon coating. In addition to the complex manufacture in two steps in which first the support structure to be coated is provided and, subsequently, is coated with silicone or a silicone gel, such wound dressings have the disadvantage that in case of defects of the enveloping structure detached fibers of the support structure may penetrate into the wound and may cause infections. By ingrowth of the tissue into the fibers of the support structure, a non-traumatic removal of the wound dressing is also at risk.
The invention has therefore the object to provide a primary dressing with a reduced inflammation risk and to provide methods for its manufacture.